A little piece of wisdom.
So your thinking about building a buggy. I thought at this point it might be good to awaken all you idealists to the realities of such a project. You need to remember three basic facts if you are going to do this.

1/ Cars cost money, buggies are no exception.
Buying a decent completed and registered example will cost 6 to 20k AU$. To build a new buggy you are looking at around 15k AU$ Minimum. If you can't afford this, pick something cheaper or wait until you can. Also, the more different you want your buggy to be the more it's probably going to cost. Get used to saving and not buying every new toy you find.

2/ Only you can make your buggy happen.
You need to plan EXACTLY what you want and then stick to the plan. The biggest problem I have seen with project cars is that people don't focus and get the car completed. This results in a huge financial loss. How many times have you seen the slogan "unfinished project". Don't find another project half way through. There is no such thing as the "Back Burner".

3/ Nothing really worth having is easy.
There are no overnight success stories. Whether you build it yourself or pay for it remember this. Things will take longer than expected. Items will cost abit (or alot) more than you expected. Sometimes you will want to give up. However, no matter how hard it is you will look back with Rose Coloured glasses once the car is finished (properly) and on the road.

2/ Ask lots of questions.
If you have found this page then you know how to use the web. It's time to use it big time. Contact all the local buggy retailers, builders, clubs and owners you can find. Ask them for pricelists, tips and advice about choosing a buggy kit. Listen carefully to people who have built one recently and find out which workshop/business helped them. A good workshop is vital unless you are a buggy specialist yourself.

If this is not the case, you might decide to build one.

3/ What are the rego rules.
For most of our international friends this is not an issue, however, in Australia and NSW in particular, Registration is quite an issue.
First of all. If you are restoring a previously registered buggy, you can re-register the vehicle under it's previously rego provided you have an engine no., license plate no., and/or photographic evidence of the vehicle in it's previous life. If you do not have this information (as I did not) you will have to register the car as a new project.
Make sure you know all of the relevant rules and procedures for building your car. Get them in writing or spend some time with your workshop or (consulting) engineer before you even lift a tool or spend a dollar. Ultimately the laws are there for yours and others safety.

4/ Long or short wheel base.
This depends on rego rules and what you want to use the car for. The original meyers manx had 14 inches cut out of it's pan to assist handling over dunes. If you are duning or doing tight tarmac stuff a shortened car might be just the ticket. It will turn better and will alway be potentially lighter. However it might suffer understeer more than a long (or standard) wheel base buggy and alot of them had poor jobs done re-welding and strengthening the pan after it was cut. The other disadvantage with them in NSW is that it may limit your choice of engine enormously due to Australian Design Rules.
Long wheel base buggies have alot more backseat space (if you want one). They are more family cars. They require no pan cutting and are slightly more stable on the freeway. In NSW they might be registered as rebodied beetles rather than as new cars the way shortened buggies have to be.

5/ What will power it?
How much power do you want. Buggies have a great power to weight ratio as is so massive power is more likely to make the car uncontrollable (especially for shortened cars). The VW engine is the obvious easy choice but serious working is expensive.
If you are using a watercooled engine, you want to pick an engine that is compact and not too long. Rotaries (mazda), boxer engines (subaru, alfa) and V6s 4 cylinders are good value for this. You will need an adapter plate. Look for an engine that will mate well to a VW transaxle unless you want to spend big bucks on a gearbox. Remember that standard 091 (2ltr kombi) and LBug boxes (both IRS) can take 200hp max and they are the strongest transaxles VW made. However, there are plenty of ratios and diffs available to beef up 091 boxes if you want to have a more powerful engine.

6/ Swingaxle or IRS.
Ultimately, IRS (independant rear suspension), as found on later beetles, is a better and more tunable suspension system. For long travel, predictable geometry and max power, much more can be done with this system. It is also much better for serious circuit racing. However, for drag racing and tight dirt racing, swingaxle is prefered by many. American tuners in particular seem to almost ignore IRS for street cars. Swingaxle chassis can fairly easily be converted to the newer IRS system using the nescesary components by a good workshop or engineer. This is best done when the pan is stripped down for the buggy.

For New South Wales people, here is the link the RTA list of Engineering Signatories. Before you do anything else, speak to one who will be willing to certify a buggy and figure out what they want first.

NOTE: Registration Laws are subject to regular changes. I do not pretend to know the specifics of them from month to month. Please consult your local authorities.